Astronomers capture an unprecedented view of gas giant formation in action

In recent decades, astronomers have reconstructed a fairly complete scenario for planet formation, from minute dust motes clumping together to the emergence of rocky spheres thousands of kilometers across, like Earth, or larger gas giants like Jupiter.

Key elements of that scenario are supported by simulations and measurements, but direct observations (“can’t we just watch how planets form?”) have been notoriously absent.

Now, a team of astronomers led by Myriam Benisty at the Max Planck Institute for Astronomy has captured a new image of planet formation in action. Taken with the ALMA observatory in Chile, the image shows the interactions between WISPIT 2b, a gas giant with five times the mass of Jupiter, and the surrounding gas of its birthplace. Their two papers are available on the arXiv preprint server.

Protoplanetary disks and their structures

Planets are born in protoplanetary disks consisting of gas and dust, which occur naturally around newly formed stars. Planets form when dust within those disks clumps together. First, larger pebbles form, then clump further to form planetesimals a few to a hundred kilometers in size.

Those planetesimals join to form rocky, planet-size spheres. In a gas-rich part of the disk, such rocky spheres can collect large amounts of gas and become the cores of gas giants like Jupiter or Saturn.

Observational evidence for this scenario has mostly been indirect. Only within the past decade or so have new facilities given astronomers a more detailed look. In 2014, after the millimeter/submillimeter observatory ALMA became fully operational, it delivered the first images of ring-like structures in protoplanetary disks, thought to be caused by young planets.

In 2018, astronomers led by Miriam Keppler, then a doctoral student at MPIA, used the SPHERE instrument at ESO’s Very Large Telescope to produce the first confirmed image of a protoplanet inside a protoplanetary disk: PDS 70b, within the disk surrounding the star PDS 70.

Introducing the WISPIT 2 system

At a distance of only about 370 light-years from us, the PDS 70 system is close enough for detailed observations. What the system does not currently provide is a chance to study the interaction between a protoplanet and gas in its immediate surroundings. The planets of PDS 70 seem to have cleared their close neighborhoods of gas rather effectively.

Enter a new contender: the WISPIT 2 system, whose discovery was announced in August 2025. It is only the second disk in which a protoplanet can clearly be seen. WISPIT 2 is named after the search program that led to its discovery (“WIde Separation Planets In Time”). It is located 430 light-years from Earth.

The system’s first known planet, WISPIT 2b, a gas giant, was discovered in parallel with the SPHERE instrument at ESO’s VLT and the 6.5 m Magellan Clay telescope. The signature light of hot hydrogen (the “Hα line”) indicates that the planet is still accreting gas from its surroundings, growing ever more massive.

The discovery of a second planet, WISPIT 2c, was announced in March 2026, based on observations with the VLT instruments SPHERE and GRAVITY+. In an additional twist, work by MPIA doctoral student Cade Bürgy published in August 2026 shows that at the center of the disk, instead of a single star, there are two stars in a very close orbit.

The challenge of fine details

A key challenge in exploring planet formation using astronomical images is the minute scale of the structures involved. If someone standing 2 meters (about 7 feet) away from you were to hold up a book, would you be able to read the text? How about 10 meters (about 33 feet)? At the distance of WISPIT 2, imaging a structure as large as the Earth–sun distance (“one astronomical unit”) is as difficult as reading an ordinary book from 5 kilometers (about 3 miles) away.

When it comes to gas and dust in protoplanetary disks, only one facility can provide the desired level of detail: the ALMA observatory, an array of 66 radio dishes on the Chajnantor plateau in the Chilean Andes, operated by an international consortium of partners.

ALMA’s antennas can be combined to be as sharp-sighted as a giant single telescope with a diameter of up to 16 kilometers (about 10 miles). Once the discovery of WISPIT 2b was announced, using ALMA to look at its gas and dust was the logical next step.

Pointing ALMA at the WISPIT 2 system

In September 2025, with the observatory in one of its most powerful configurations for detailed imaging, the ALMA antennas turned toward WISPIT 2b. Additional observations followed in November 2025 and March 2026.

The observations had been planned and proposed by a team led by Stefano Facchini of the University of Milan and including Benisty, who is the director of the Planet Formation and Exoplanets (PFE) department at MPIA.

Facchini, Benisty and other team members were well positioned to take on the challenge: In previous years, they had been part of the exoALMA project, honing their skills to extract as much information as possible from ALMA observations of protoplanetary disks. Benisty had also been part of the collaboration that discovered WISPIT 2b.

The combination of a powerful observatory and highly skilled analysis paid off. The team took images of the dust and gas as detailed as any previously taken of a protoplanetary disk. Particularly rewarding was the effort to image the gas in the disk.

Benisty, who led this part of the project, says, “We clearly see both planets shaping their environment. WISPIT 2c has carved a cavity, and WISPIT 2b a gap. Around WISPIT 2b, we find swirls of gas that had been predicted by simulations of disk-planet interactions, but never actually seen before. Now there is an image of them!”

This makes WISPIT 2b the only protoplanet for which we can see the protoplanetary disk, the planet, evidence that the planet is still accreting and, as the final piece of the puzzle, gas interacting directly with the planet. Planet formation in action.

Putting the new discovery to work

Once joined by other observations of its kind, the new result could help resolve an important open question in the field. Swirls on their own, without the direct detection of a planet, have been seen in other protoplanetary disks. Some researchers argue these swirls indicate the presence of an unseen planet. Others have pointed to turbulent processes in such disks that may explain the features without a planet.

The new observations are the first example of a system where we see both the swirling features and the associated planet. “Hopefully, observations like this will teach astronomers to distinguish between disk features that indicate the presence of a protoplanet and features that don’t,” says Facchini, leader of the ALMA observation proposal that yielded the new results.

The present result concerns a gas giant at a considerable distance (57 au) from the central stars, almost twice as far as Neptune is from the sun. Almost all known exoplanets are much closer to their central stars. But the methods used in the analysis pave the way for observations with the next generation of instruments, including ESO’s 39 m Extremely Large Telescope and a planned upgrade of the ALMA antennas that would significantly improve sensitivity.

In a bit over a decade, those tools could provide an updated version of the present result: an action picture of a gas giant at the same distance from its star as Jupiter or Saturn is from the sun—and, hopefully, new insights into how such gas giants help shape a solar system like our own.

Who’s behind this story?

Swati Mestri

Swati Mestri holds a bachelor’s degree in Electronics Engineering and has worked as a content editor since 2019. She has experience editing research documents across technology, health care, and materials science, and has a particular interest in technology and space.

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Robert Egan

Bachelor’s in mathematical biology, Master’s in creative writing. Well-traveled with unique perspectives on science and language.

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